The present invention relates to tires and more particularly the way in which the carcass reinforcement cords are arranged and the way in which they are anchored in the beads.
U.S. Pat. No 5,660,656 has recently proposed a novel type of tire carcass casing and a way of anchoring it in its two beads. A tire, in these applications, comprises a crown, two sidewalls and two beads, a carcass casing anchored in the two beads comprising cords worked back and forth next to each other aligned circumferentially with, in each bead, loops each connecting back and forth cord portions, and in each bead, means of anchoring the carcass casing comprising piles of cords oriented circumferentially and axially bordering said circumferential rows of said back and forth arrangement of carcass casing cords. In these tires, the taking up of the tension which is developed in the carcass upon inflation is solely achieved by the adherence of each carcass cord laterally with the anchoring means.
These applications also propose, when the carcass casing needs to be so strong that it is no longer geometrically possible to arrange the cords in the beads in a single circumferential row, that a single circumferential back and forth row be conserved in each sidewall and that this row be split into two rows which progressively diverge axially from one another from a sidewall towards the base of a bead.
The advantage of this solution is that it maintains a great deal of flexibility in the sidewalls while at the same time enabling the use of a higher density of cords, therefore making it possible to increase the number of carcass cords above which it becomes necessary to resort to a separate additional carcass on account of a lack of space in the bead in which to house all the cords.
It has been observed that it is very tricky to produce such a tire with a carcass casing made up of a circumferential row of cords in the crown and in the sidewalls which splits into two at the beads. This is because the industrialization constraints are such that it is difficult to prevent a certain number of the cords coming into contact with one another, and this can lead to endurance problems.
The object of the present invention is to overcome this problem.